Short Answer When mold appears, German courts make the landlord move first: he must prove the dampness is not caused by the building itself — its insulation, pipes, or thermal bridges — before any blame can reach you. Only once structural causes are excluded does the burden shift to your heating and ventilation habits, which is where landlords' forensic inspectors earn their fees. What Most Expats Don't Realize You discovered a large patch of black mold forming directly behind your bedroom headboard and assumed the property owner would automatically pay for the cleanup. The landlord's inspector first ruled out structural defects — the step the law demands from his side — and then demonstrated that your furniture was pushed tight against a cold outer wall, blocking the necessary air circulation. Because the second stage of the evidentiary ladder landed on your daily habits, you were held liable for the remediation costs, resulting in a bill of €1,750. What To Do * Pull all large furniture items at least ten centimeters away from any external walls to permit continuous airflow. * Email a formal, written notification accompanied by high-resolution photos to your landlord the exact day a dark spot appears. * "Ich melde hiermit einen Schimmelbefall in der Wohnung." (I am hereby reporting a mold infestation in the apartment.) — send this written declaration immediately to avoid accusations of hiding damage. The Truth Germany's housing courts run mold disputes as a two-stage evidentiary ladder, and the landlord's experts are paid to climb past the first stage as fast as possible. The system protects tenants on paper — but only the ones whose photos, dates, and ventilation routines are documented well enough to survive the second stage.